Mounting Promise RAID0 w/ Linux software RAID

Mounting Promise RAID0 w/ Linux software RAID

[Aaron Longfield]

Hi,

I am trying to recover data from a stripe set (RAID0) that was written 
using the sort-RAID functions of a Promise UDMA-133 Fasttrak controller. 
    The mainboard with that controller has died, and I don't have 
another one around to try to run the discs on!

I've been able to start and mount the array, but I think I'm only 
getting the first stripe or something that's on the first disc.

I know the stripe size had been 64kb and there were two discs in the 
array.  The first disc has a proper partition table, but it's for the 
full array, as would be on a Linux md device.  I'm having trouble 
figuring how I would even try to specify this...

Does anyone happen to have any suggestions on this one?  I don't want to 
have the scrap the data, or buy another piece of hardware with one of 
those controllers on it!

Here's the partition tables:

	Disk /dev/hdl: 122.9 GB, 122942324736 bytes
	255 heads, 63 sectors/track, 14946 cylinders
	Units = cylinders of 16065 * 512 = 8225280 bytes

	   Device Boot    Start       End    Blocks   Id  System
	/dev/hdl1   *         1     29893 240115491    7  HPFS/NTFS

	Disk /dev/hdj: 122.9 GB, 122942324736 bytes
	16 heads, 63 sectors/track, 238216 cylinders
	Units = cylinders of 1008 * 512 = 516096 bytes

	Disk /dev/hdj doesn't contain a valid partition table

And here's the raidtab:

raiddev /dev/md2
         raid-level              0
         nr-raid-disks           2
         persistent-superblock   0
         chunk-size              64

         device                  /dev/hdl1
         raid-disk               0
         device                  /dev/hdj
         raid-disk               1

Partitioning on RAID (Ref: Mounting Promise RAID0 w/ Linux software RAID)

[Aaron Longfield]

I found that I can combine the discs raw into one large array that maps 
properly.  Problem is that now I have an array that has a partition 
table and a partition that I can't seem to mount.  Is there any way to 
coax the system into letting me do this?  I couldn't find any 
documentation on it, but there seems to be support in the kernel code 
for the md driver.

-Aaron Longfield

Partition on the array:

Disk /dev/md0: 245.8 GB, 245884649472 bytes
255 heads, 63 sectors/track, 29893 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

     Device Boot	     Start	   End	    Blocks    Id  System
/dev/md0p1   *		 1	 29893	 240115491     7  HPFS/NTFS


raidtab entry:

raiddev /dev/md0
	raid-level		0
	nr-raid-disks		2
	persistent-superblock	0
	chunk-size		64

	device			/dev/hdc
	raid-disk		0
	device			/dev/hdd
	raid-disk		1

Re: Partitioning on RAID (Ref: Mounting Promise RAID0 w/ Linux software RAID)

[Ricky Beam]

On Thu, 1 Jul 2004, Aaron Longfield wrote:
>properly.  Problem is that now I have an array that has a partition
>table and a partition that I can't seem to mount.  Is there any way to
>coax the system into letting me do this?  I couldn't find any
>documentation on it, but there seems to be support in the kernel code
>for the md driver.

It actually is documented... Documentation/md.txt.  The "magic" is the
raid device's major number:
	[root:pts/8]spork:~/[12:36 PM]:cat /proc/devices |grep 'md\|Block'
	Block devices:
  	9 md
	254 mdp

"mdp" is dynamically allocated, so booting to a partitioned soft-raid is
tricky, but certainly do able.

Simply change your raid device from /dev/md0 (which is major #9) to something
with a major number matching mdp.  In my case:
	[root:pts/8]spork:~/[12:36 PM]:ls -l /dev/md0
	brw-rw----  1 root disk 9, 0 Feb 23 16:04 /dev/md0
	[root:pts/8]spork:~/[12:38 PM]:ls -l /dev/md
	total 0
	brw-r--r--  1 root root 254, 0 Jun  9 21:04 d0
	brw-r--r--  1 root root 254, 1 Jun  9 21:04 d0p1
	brw-r--r--  1 root root 254, 2 Jun  9 21:04 d0p2
	brw-rw----  1 root disk 254, 3 Jun 17 15:09 d0p3

	[root:pts/8]spork:~/[12:38 PM]:fdisk -l /dev/md/d0

	Disk /dev/md/d0: 640.1 GB, 640167510016 bytes
	255 heads, 63 sectors/track, 77829 cylinders
	Units = cylinders of 16065 * 512 = 8225280 bytes

	      Device Boot      Start         End      Blocks   Id  System
	/dev/md/d0p1               1       72606   583207663+   7  HPFS/NTFS
	/dev/md/d0p2   *       72607       77306    37752750   83  Linux
	/dev/md/d0p3           77307       77828     4192965   82  Linux swap

--Ricky

PS: The above naming scheme requires a small patch to grub to make it name
the partitions correctly.  By default, it'll look for /dev/md/d01, etc.

RESOLVED Re: Partitioning on RAID (Ref: Mounting Promise RAID0 w/ Linux software RAID)

[Aaron Longfield]

Thanks a bunch, piecing together what you told me, a bit of a few 
messages that I found from the mailing list a long while ago, and Neil's 
old patches, I think I have it working!

The trick seemed to be using mdadm to bring the array up:

mdadm -B /dev/md/d0 /dev/hdc /dev/hdd --level=raid0 --raid-devices=2

The node for the d0p1 block device was not auto-created even though I 
have devfs, but after creating one for "254,1", I was able to mount the 
partition.

This is wonderful, and hopefully I can get small bit of info in the RAID 
FAQ or HOWTO about it.  I didn't see anywhere a reference to being able 
to start a Promise Fasttrak array with just the Linux RAID code. :)

-Aaron Longfield

Ricky Beam wrote:
> On Thu, 1 Jul 2004, Aaron Longfield wrote:
> 
>>properly.  Problem is that now I have an array that has a partition
>>table and a partition that I can't seem to mount.  Is there any way to
>>coax the system into letting me do this?  I couldn't find any
>>documentation on it, but there seems to be support in the kernel code
>>for the md driver.
> 
> 
> It actually is documented... Documentation/md.txt.  The "magic" is the
> raid device's major number:
> 	[root:pts/8]spork:~/[12:36 PM]:cat /proc/devices |grep 'md\|Block'
> 	Block devices:
>   	9 md
> 	254 mdp
> 
> "mdp" is dynamically allocated, so booting to a partitioned soft-raid is
> tricky, but certainly do able.
> 
> Simply change your raid device from /dev/md0 (which is major #9) to something
> with a major number matching mdp.  In my case:
> 	[root:pts/8]spork:~/[12:36 PM]:ls -l /dev/md0
> 	brw-rw----  1 root disk 9, 0 Feb 23 16:04 /dev/md0
> 	[root:pts/8]spork:~/[12:38 PM]:ls -l /dev/md
> 	total 0
> 	brw-r--r--  1 root root 254, 0 Jun  9 21:04 d0
> 	brw-r--r--  1 root root 254, 1 Jun  9 21:04 d0p1
> 	brw-r--r--  1 root root 254, 2 Jun  9 21:04 d0p2
> 	brw-rw----  1 root disk 254, 3 Jun 17 15:09 d0p3
> 
> 	[root:pts/8]spork:~/[12:38 PM]:fdisk -l /dev/md/d0
> 
> 	Disk /dev/md/d0: 640.1 GB, 640167510016 bytes
> 	255 heads, 63 sectors/track, 77829 cylinders
> 	Units = cylinders of 16065 * 512 = 8225280 bytes
> 
> 	      Device Boot      Start         End      Blocks   Id  System
> 	/dev/md/d0p1               1       72606   583207663+   7  HPFS/NTFS
> 	/dev/md/d0p2   *       72607       77306    37752750   83  Linux
> 	/dev/md/d0p3           77307       77828     4192965   82  Linux swap
> 
> --Ricky
> 
> PS: The above naming scheme requires a small patch to grub to make it name
> the partitions correctly.  By default, it'll look for /dev/md/d01, etc.